Silver halide color photographic recording materials typically comprise a support onto which are applied distinct layers which vary in composition and function. Some of these layers include silver halide emulsions sensitized to a specific spectral region. Generally there are at least three sensitized silver halide layers in a color photographic material, a cyan dye layer, a magenta dye layer and a yellow dye layer. Additionally, these silver halide color photographic materials will often employ two, three or more layers which vary in the degree of sensitivity to a specific spectral region, for example a fast cyan layer and a slow cyan layer.
Other layers are incorporated for ancillary purposes which include, but are not limited to, isolating the light sensitive silver halide layers from one another and protecting the light sensitive silver halide emulsions from handling and environmental damage. Many arrangements and combinations of such individual layers are known in the art.
Various compounds, particularly couplers, that are capable of releasing a development inhibitor during photographic processing are known in the photographic art. Examples of such compounds are described in U.S. Pat. Nos. 3,227,554; 3,384,657; 3,379,529; 3,615,506; 3,617,291; 3,620,746; 3,701,783; 3,733,201; 4,049,455; 4,095,984; 4,248,962; 4,409,323; and 4,962,018, as well as in "Development-Inhibitor-Releasing (DIR) Couplers in Color Photography", C. R. Barr, J. R. Thirtle and P. W. Vittum in Photographic Science and Engineering, vol. 13, page 174 (1969).
Development inhibitor releasing compounds, known as DIR compounds, are used in silver halide color photographic materials to influence many photographic properties. These uses include but are not limited to the control of intralayer developability, i.e. the control of the gamma of a photographic layer with which they are reactively associated and the control of interlayer interimage effects, i.e. the control of the developability or gamma of other photographic layers . They can also be used to control granularity and sharpness.
One use of development inhibitors is to affect the color saturation of a color image. The color saturation of an object is the colorfulness of that object as judged in proportion to the brightness of an otherwise similar gray object. In a like vein, the color saturation attained in a photographic image of an object is related to the differences between the color densities formed in photographically reproducing that object and the color densities formed in photographically reproducing an otherwise similar (as to brightness) gray object. These differences in color density formation resulting from differences in the color of an object can be augmented by several means. One of these means is by application of the Interlayer Interimage Effect (IIE) as induced by the imagewise release of a development inhibitor from a DIR compound during development of the photographic material.
In practice, high levels of color saturation can be attained when a color photographic material is designed such that development inhibitors released as a function of development in one color record have a large development inhibiting effect on development in the other color records. By this expedient, the color densities formed in photographically reproducing a colored object are caused to be greatly different from the color densities formed in photographically reproducing an otherwise similar (as to brightness) gray object. For example, the red density produced in a negative image of a red object will be greater than the red density produced in a negative image of an otherwise similar (as to brightness) gray object when development inhibitors released as a function of development in a green-light or blue-light sensitive layer (layers rendered developable by exposure to the gray object but not by exposure to the red object) have a large development inhibiting effect on the red-light sensitive layer. However, often during processing the development inhibitors diffuse out of the photographic element before they can fully enhance color saturation thus leaving a finished product which is dull and unappealling. One method of increasing color saturation is to retain the development inhibitor within the photographic element.
It is known to utilize scavenger layers for released development inhibitors to prevent the diffusion of such inhibitors. Such scavenger layers include the use of Lippmann emulsions in layers above, between or below image forming emulsion layers to inhibit the migration of development inhibitor either between layers or from the element to the developing solution other inhibitor adsorbing layers are described in U.S. Pat. Nos. 3,984,245 and 4,055,429. Polymers which mordant or scavenge development inhibitor, however, remove it from the system and the photographic material would require a higher concentration of DIR compound to provide the desired color saturation.
A need still exists for a color photographic silver halide element showing a high degree of color saturation and a means of conveniently adjusting the degree of color saturation provided by such an element. Use of DIR compounds alone has not proven adequate to fully meet the needs of users of such color recording materials while the use of scavenging or mordanting polymers or other mordanting species in combination with DIR compounds does not adequately address this need.